Equilibrium and rate constants for the following types of protonic reactions are being obtained in the gas phase utilizing ion cyclotron resonance spectroscopy: A1H ion plus A2 reversible yields A2H ion plus A1, A1H ion B plus A2 reversible yields A2H ion B plus A1, AH ion B1 plus B2 reversible yields AH ion B2 plus B1. The work involves basic molecules, i.e., A, A1, A2, B, B1, and B2, which contain functional groups of biological importance. Emphasis is placed upon conjugate acids of pyridine derivatives as well as cations of the OH, NH, SH, and PH ions types. A major objective of the experimental and theoretical investigations is to determine the number of water molecules that are bound to the AH ion conjugate acids which are responsible for the strong chemican and biological specificities found in aqueous environments. F-nmr shielding parameters for appropriately substituted fluorobenzenes are being utilized in sensitive studies of hydrogen bondin of both ionic and neutral substrates with solvents. A quantitative model for treating hydrogen-bonding medium effects has been proposed. Critical tests of the treatment are being made.